Method using capacitive sensors for morphology discrimination of a passenger seating in an automotive seat

• US 7,962,311 B2
• Filed: 06/21/2007
• Issued: 06/14/2011
• Est. Priority Date: 06/23/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi Computer Products (Europe) SAS (Hitachi, Ltd.)
• Original Assignee: Hitachi Computer Products (Europe) SAS (Hitachi, Ltd.)
• Inventors: Ninomiya, Takanori, Maeda, Shunji, Voisin, Florent, Launay, Claude, Da Silva, Joaquim, Hirai, Tomoaki
• Primary Examiner(s): Charioui; Mohamed
• Application Number:
  US11/820,963
• Publication Number:
  US 20080021650A1
• Time in Patent Office: 1,454 Days
• Field of Search: 702/1, 702/33, 702/41, 702/52, 702/54, 702/56, 702/129, 702/158, 702/173, 702/189, 702/193, 701/45, 701/49, 340/541, 340/561
• US Class Current: 702/158
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors

Abstract

The present invention relates to a method for discriminating the morphology of a passenger seating in an automotive seat, comprising the steps of i) providing a set of a plurality of capacitive sensors (100) covering substantially a transversal cross section of a seat, ii) collecting the outputs of said plurality of capacitive sensors (100) provided on the seat, iii) determining the morphology of a target (10) facing the seat on the basis of measured distance separating the target (10) from the sensors (100) and measured surface of the sensors (100) covered by the target (10), from said outputs, and iv) comparing the determined morphology with at least a reference so as to classify the determined morphology between a plurality of reference ones.

Claims

1. A method for discriminating the morphology of a passenger seating in an automotive seat, comprising the steps of

i) providing a set of a plurality of capacitive sensors covering substantially a transversal cross section of a seat,

ii) collecting the outputs of said plurality of capacitive sensors provided on the seat,

iii) determining the morphology of a target facing the seat on the basis of measured distance separating the target from the sensors and measured surface of the sensors covered by the target, from said outputs, by selecting a value representative of the distance (di) separating the target from the sensor, from a look up table, using as input for this selection a combination of the outputs issued by the capacitive sensor and selecting a value representative of the amount (Sdi) of the surface of the sensor covered by said target, from another look up table, using also as input for this selection a combination of the outputs issued by the capacitive sensor, and

iv) comparing the determined morphology with at least a reference morphology so as to classify the determined morphology between a plurality of reference morphologies,

wherein the comparing step involves a mathematical function of Gaussian type.

5. The method of one of claims 1 or 2-4, characterized in that it comprises a step of rejecting all measurements that are not coherent with a passenger outline.

6. The method of one of claims 1 or 2-4, characterized in that the comparing step involves a mathematical function S(p) representing a morphology reference.

7. The method of one of claims 1 or 2-4, characterized in that the comparing step comprises applying bothan evaluation of profile measurements in regard of a template andan evaluation in regard of a reference plane, and then selecting the evaluation which leads to the minimum error criteria.

8. The method of one of claims 1 or 2-4, characterized in that the method implements a capacitive sensor comprising at least two electrodes covering complementary respective areas of a sensed zone so as to form two balanced pixel sensors.

9. The method of one of claim 1 or 2-4, characterized in that the method implements a capacitive sensor comprising three electrodes:

two main electrodes covering complementary respective areas of a sensed zone and a third auxiliary electrode covering both said complementary respective areas.

10. The method of one of claim 1 or 2-4, characterized in that the method implements a capacitive sensor wherein said third auxiliary electrode surrounds the two main electrodes.

11. The method of one of claim 1 or 2-4, characterized in that comprises the steps of

collecting the outputs of a plurality of capacitive sensors provided on a seat,

determining for each capacitive sensors a first value representative of the distance (di) separating a target from the sensor and a second value (Sdi) representative of the surface of the sensor covered by the target,

applying to the second values (Sdi) representative of the surface of the sensor covered by the target a respective weighting (Wi) based on the corresponding first value (di) representative of the distance separating the target from the sensor covered by the target, and

determining the morphology of the target on the basis of the collection of weighted second values (Sdi×

Wi).

12. The method of one of claims 1 or 2-4, characterized in that the method implements at least four sensors substantially aligned from left to right on a seat.

13. The method of one of claims 1 or 2-4, characterized in that the method implements look up tables which contain values representative of the distance (di) separating the target from the sensor or values representative of the amount (Sdi) of the surface of the sensor covered by said target, for a plurality of temperature and humidity values, and the method comprises the step of selecting in the look up tables an output value depending on a combination of the outputs issued by the capacitive sensor which represents real temperature and humidity.

14. Seat for an automotive car characterized in that it comprises means for implementing the method in accordance with one of claims 1 or 2-4.

2. A method for discriminating the morphology of a passenger seating in an automotive seat, comprising the steps of

i) providing a set of a plurality of capacitive sensors covering substantially a transversal cross section of a seat,

ii) collecting the outputs of said plurality of capacitive sensors provided on the seat,

iii) determining the morphology of a target facing the seat on the basis of measured distance separating the target from the sensors and measured surface of the sensors covered by the target, from said outputs, by selecting a value representative of the distance (di) separating the target from the sensor, from a look up table, using as input for this selection a combination of the outputs issued by the capacitive sensor and selecting a value representative of the amount (Sdi) of the surface of the sensor covered by said target, from another look up table, using also as input for this selection a combination of the outputs issued by the capacitive sensor, and

iv) comparing the determined morphology with at least a reference morphology so as to classify the determined morphology between a plurality of reference morphologies,

wherein the comparing step involves a Bell like function S(p) of order n:

15. The method of claim 2, characterized in that the comparing step comprises determining if a profile measurement corresponds to the shape of a mathematical function.

16. The method of claim 2, characterized in that determining if a profile measurement corresponds to the shape of a mathematical function comprises calculating an error criteria.

17. The method of claim 2, characterized in that it comprises calculation for each profile measurement of the parameter “

a”

by;

determining the surface S under the profile measurement;

18. The method of claim 17, characterized in that the equalizing step is performed by using a lookup table for S_b.

3. A method for discriminating the morphology of a passenger seating in an automotive seat, comprising the steps of

i) providing a set of a plurality of capacitive sensors covering substantially a transversal cross section of a seat,

ii) collecting the outputs of said plurality of capacitive sensors provided on the seat,

iii) determining the morphology of a target facing the seat on the basis of measured distance separating the target from the sensors and measured surface of the sensors covered by the target, from said outputs, by selecting a value representative of the distance (di) separating the target from the sensor, from a look up table, using as input for this selection a combination of the outputs issued by the capacitive sensor and selecting a value representative of the amount (Sdi) of the surface of the sensor covered by said target, from another look up table, using also as input for this selection a combination of the outputs issued by the capacitive sensor, and

iv) comparing the determined morphology with at least a reference morphology so as to classify the determined morphology between a plurality of reference morphologies,

wherein the comparing step involves a 3D reference image representing a morphology reference.

19. The method of claim 3, characterized in that the comparing step involves construction of a n by m mesh, by interpolation of the profile measurements, to create a profile, wherein in said n by m mesh comprises a plurality of pixels, each pixel having a pixel value.

20. The method of claim 19, characterized in that the construction of the n by m mesh is operated on the basis of the following rules:

for the pixels of the mesh where there is no probe, the pixel value is interpolated from the nearest probes,

for the areas of the mesh where there is more that one pixel to interpolate between two measured pixels, the intermediate pixels values are linearly interpolated between the measured pixels over the distance separating them.

21. The method of claim 19, characterized in that the construction of the n by m mesh comprises generating some pixels of the mesh by interpolation between a measured pixel and a previously interpolated pixel.

22. The method of claim 3, characterized in that the comparing step comprises comparing a profile measurement with a maximal template limit and with a minimal template limit.

23. The method of claim 3, characterized in that the comparing step comprises counting the number of pixels of a profile measurement that belongs to the template.

4. A method for discriminating the morphology of a passenger seating in an automotive seat, comprising the steps of

i) providing a set of a plurality of capacitive sensors covering substantially a transversal cross section of a seat,

ii) collecting the outputs of said plurality of capacitive sensors provided on the seat,

iii) determining the morphology of a target facing the seat on the basis of measured distance separating the target from the sensors and measured surface of the sensors covered by the target, from said outputs, by selecting a value representative of the distance (di) separating the target from the sensor, from a look up table, using as input for this selection a combination of the outputs issued by the capacitive sensor and selecting a value representative of the amount (Sdi) of the surface of the sensor covered by said target, from another look up table, using also as input for this selection a combination of the outputs issued by the capacitive sensor, and

iv) comparing the determined morphology with at least a reference morphology so as to classify the determined morphology between a plurality of reference morphologies,

wherein the comparing step comprises calculating a distance between a profile measurement and a reference plane.

24. The method of claim 4, characterized in that the distance to the reference plane in calculated as follows:

25. The method of claim 4, characterized in that the distance to the reference plane in calculated using a normalized version for the distance: